The present invention relates to a motor structure, and more particularly to a motor structure having lower profile.
Recently, electrical devices trend to be compact. For example, notebook computers are getting thinner and thinner. To meet the demand of compact electrical device, a fan having lower profile is required.
In developing the fan having lower profile, the most important problem is that the stator of the conventional motor cannot meet the requirement of the designer, and there are difficulties in manufacturing a stator having lower profile.
FIG. 1 is a partial cross-sectional view illustrating a conventional motor structure. FIG. 2 is a side view illustrating the conventional motor structure shown in FIG. 1 Referring to FIG. 1 and FIG. 2, the motor structure includes a magnetic ring 100 and a stator 200. The magnetic ring 100 is a part of a rotor (not completely shown). The stator 200 includes a silicon steel set 201 with four poles and a coil (wirings) 202 wound on the silicon steel set 201.
Since the silicon steel set 201 is composed of a plurality of silicon steel sheet stacked together, the edges of the silicon steel set 201 are sharp. Therefore, a film or cover (not shown) is needed to cover the silicon steel sheet 201 for winding the coil 202 without damaging them.
In the above-mentioned motor structure, the method of winding of the coil wastes a lot of space, that is, the coil cannot totally fill the circular area surrounded by the silicon steel set 201, deteriorating the performance of the motor.
In order to make the above-mentioned motor structure thin, there may occur the following effects:
(a)since the number of the silicon steel must be relatively small and the space for the winding is insufficient, the motor performance is relatively poor.
(b)since the size of the stator is relatively small and the tolerance is relatively strict, the difficulty level is increased in manufacturing and assembling the motor; and
(c)since the edge of the silicon steel sheet of a thin stator are relatively sharp, the wirings wound thereon are easily damaged and short-circuit the coil.
In general, the stability of the operating motor depends on the number of poles of the motor. In the above-mentioned motor structure, the number of poles thereof is four. If the number of poles is increased to eight, undesirable problems occur. For example, difficulty in winding the wirings may occur. Also in a condition that seldom occurs, the motor may easily short out or the performance thereof will be poor.
Therefore, the main object of the present invention is to provide a motor structure having lower profile capable of improving the performance and facilitating the manufacturing processes.
The above object of the present invention is achieved by providing a motor structure including a stator having a coil seat, and a rotor having a circular magnet located above the coil seat. The coil seat is defined by a bottom plate, a plurality of first teeth and a plurality of second teeth. The first teeth are formed around the inner periphery of the bottom plate. The second teeth are formed around the outer periphery of the bottom plate. Each of the first teeth and the second teeth further includes a first extending portion and a second extending portion, respectively.
The motor structure further has a base for accommodating the coil seat. Alternatively, the coil seat is formed on an optional concavity of the base.
Furthermore, the stator further includes a shaft substantially perpendicular to, and fixed on the base. A ring-shaped groove is formed on the shaft. The rotor also includes a hub, a metal sheet, and a bearing. The metal sheet, arranged between the hub and the circular magnet, is used to avoid magnetic leakage. The shaft penetrates the bearing. The motor structure may further include an engagement ring and an elastic ring. The engagement ring is positioned on the bearing for fixing the bearing. The elastic ring is positioned in the ring-shaped groove for elastically fixing the bearing. The engagement ring and the elastic ring are used to fix the bearing so as to prevent the bearing and the shaft form separating along the axial direction of the shaft.